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PostPosted: Tue May 23, 2017 11:33 pm 
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Joined: Tue Jan 12, 2016 7:50 pm
Posts: 172
Location: Tulsa Ok
I think I found the wheels that I want to get but this Offset or back spacing is confusing me. I am looking at a set of ZL1 wheels. They are 20x9 frt @ +27 and 20x10 rear @ +35 I am thinking of running 265 x 35 x 20 Nitto 555 G2 tires all around and I will be dropping the PPV down by using the OEM SS springs. I believe this to be a 3\4 inch drop.
So, will this Staggered combo work or should I change, say, run the 9 inch +27 all the way around or run the 10 inch with +35 all the way around? Or am I as dumb about all of this as I think I am and I would be stupid if I did any of this. lol I may have asked this as I have been rolling this in my mind for a while, but I don't seem to remember ever getting a good answer if I did ask. ( Gray hair and I have slept once or twice )

1991 Honda Night Hawk 750
2000 Silver Trans Am (RIP)
2005 Jeep Grand Cherokee Extreme
2013 Silver Caprice PPV

PostPosted: Wed May 24, 2017 2:13 am 
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Joined: Tue Mar 19, 2013 11:30 pm
Posts: 1448
Location: Canton GA
I don't mean to rain on your parade, but here goes:

As a point of reference, 2010-2015 Camaro SS wheels are 20x8 front +35mm. and 20x9 rear +40mm

Here's a link to a tire/wheel "calculator" that may help:

If you plug in the above wheels, then do a comparison with the ZL1 wheels you're lusting over, you'll see what it shows.

Without actually running the numbers, I can tell you that the Camaro SS front wheel works fine in front, with a 255/35-20 tire, on a lowered PPV

I can also tell you that the Camaro SS rear wheel, with a 275/30-20 tire, on a lowered car, has interference issues with the wheel opening sheetmetal--in other words, the fenders have to be rolled.

So, if you go to a ZL1 front wheel that is a full inch wider than the SS (front) wheel, combined with a LOWER offset (the wheel sits further outboard), I'm not entirely confident you will be able to do this without some clearance issues on the body, or with the wheel and/or tire hanging out of the wheel opening--not good, IMO.

In the back, comparing the ZL1 rear wheel, again a full inch wider than the Camaro SS wheel, and again with a LOWER offset, it sets up a collision course situation for the tire and the wheel opening, and a bit of wheel/tire "hanging" outside of the wheel opening--and I'm not sure this can be solved simply by rolling the fenders.

For comparison, I'm currently running a square 8.5" wheel setup with 255/40-19's, offset is +38mm--and I use a 3mm hub-centric spacer on front, and 4mm hub-centric spacer on the rear, which effectively means +35mm front and +34mm rear. To push any further (and the car is not yet lowered) I know there would be issues in back--I might be able to remove the 4mm spacers and recover enough clearance to be a non-issue. I'm using the spacers for their hub-centric feature, and in anticipation of moving the (front) wheel away from the Brembo calipers when I FINALLY install them.

I believe a wheel over 9" width will need an offset of at least +40mm. The production SS Sedan wheels are 8.5 front +48mm, and 9" rear +57mm, as a point of reference. Deviations of the magnitude you're considering are going to be problematic. Unfortunately, the Camaro, even though it's also a variety of the Zeta platform, is not working with the same set of body & suspension specs and clearances as the PPV, G8, and SS Sedan.

Bill Harper

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